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It is generally known that NOx reacts with unburned gasoline, olefins in particular, to form sludge precursors. In this study, the authors investigated the process by which NOx and unburned gasoline mix into the engine oil and analyzed the mechanism whereby stop and go driving accelerates sludge formation. It has been found that NOx detected in the engine oil as nitrite ions mixes into the oil in the crankcase. The NOx concentration in the engine oil increases rapidly when the crankcase gas temperature is nearly equal to the dew point of the water vapor in the crankcase. Unburned gasoline is mainly absorbed into the oil through the oil film on the cylinder walls and the oil in the ring grooves. During low-temperature engine operation in stop-go driving (i.e., when the vehicle is stopped), NOx and unburned gasoline are absorbed into the engine oil and, in high-temperature engine operation (i.e., when the vehicle is moving), NOx and unburned gasoline are released from the oil.

In order to clarify the effect of each gasoline component on engine performance during warm-up, changes in the air-fuel ratio and quantity of wall flow (liquid gasoline on the induction port) were measured using ordinary gasolines and model gasolines consisting of a blend of several hydrocarbons and MTBE (methyl-tertiary-butyl-ether). The unburned air-fuel mixture in a combustion chamber was sampled via a solenoid valve and analyzed by gas chromatography to investigate the vaporization rate of each component. The results show that MTBE has an important effect on driveability because it contains oxygen and easily vaporizes, resulting in a lean mixture in the transient state. The popular driveability index, T50 (50% distillation temperature), does not provide an adequate means of evaluating MTBE-blended gasoline.

Hydrocarbons and other organic materials emitted from S.I. engines cause ozone to form in the air. Since each species of organic materials has a different reactivity, exhaust components affect ozone formation in different ways. The effects of exhaust emission control devices and fuel properties on speciated emissions and ozone formation were examined by measuring speciated emissions with a gas chromatograph and a high-performance liquid chromatograph. In the case of gasoline fuels, catalyst systems with higher conversion rates such as close-coupled catalyst systems are effective in reducing alkenes and aromatics which show high reactivities to ozone formation. With deterioration of the catalyst, non-methane organic gas (NMOG) emission increases, but the specific reactivity of ozone formation tends to decrease because of the increase in alkane contents having low MIR values.

An analysis was made of wear factors by investigating the effect of engine operating conditions on valve train wear. It was found that cam nose wear increased as larger amounts of combustion products, including nitrogen oxides and unburned gasoline, became intermixed with the engine oil. Based on these results, a valve train wear test procedure has been developed for evaluating cam nose and rocker arm wear under engine firing conditions. It has been confirmed that this test procedure correlates will with ASTM Sequence VE test and CCMC TU-3 test.

Nissan’s new 2.8 liter in-line 6-cylinder turbocharged engine was developed for Che Datsun 280ZX in order to achieve higher performance and improved fuel economy. The Electronic Concentrated Engine Control System (ECCS), controlled by microprocessor, is provided for this 2.8 liter turbocharged engine. ECCS controls fuel injection, ignition timing, EGR rate and idling speed. It solved the problems related to power and fuel economy by optimizing the control parameters. Further, this system contains a barometric pressure compensator and a detonation controller; thus, the performance of this engine is efficient over a wide range of circumstances and fuel octane ratings. During the development of the engine, computer simulation was employed to predict engine performance and select turbocharger size, valve timing and other important factors.